A point-of-care blood gas analyser, Edan i15 Vet (EDAN), was compared with a benchtop blood gas analyser, GEM Premier 3000 (GEM). GEM and EDAN were used to analyse whole blood from 123 lactating Holsteins within one month of calving for blood gases, electrolytes, hematocrit and hemoglobin. EDAN and GEM showed significant linear correlations for blood gases, electrolytes, Hct and Hb. The 95% confidence intervals (CI) of intercept in Passing-Bablok regressions included zero in pCO2, bicarbonate, TCO2, BE ecf, BE B, hematocrit, and pH, but not for Na+, K+, pO2 and sO2. The CI of the slope included 1.0 for Na+, K+, pCO2, bicarbonate, TCO2, BE ecf, BE B, hematocrit, and pH, but not for pO2, sO2, and hemoglobin. The Bland-Altman plots between EDAN and GEM showed a bias of 1.4% for Na+, 2.4% for K+, –1.6% for pCO2, 3.0% for pO2, –5.3% for bicarbonate, 2.8% for SO2, –7.3% for TCO2, 10.4% for Hct, 21.2% for Hb, –25.1% for BE B and –38.5% for BE ecf. The biases in the analysis of certain estimated parameters were much higher (> 5%) than for measured parameters except for Hct. Parity did not correlate with blood gas parameters but blood pH correlated negatively with K+, pCO2 and positively with pO2, TCO2, sO2, bicarbonate, BE ecf and BE B. The postpartum time correlated positively with pCO2, TCO2, BE and bicarbonate and negatively with Hct and Hb values. Reference values (2.5-97.5% quartiles) were determined for each parameter. Conclusively, EDAN can be used interchangeably with GEM for the analysis of blood pH, K+, pCO2 and HCO3 – as they show acceptable moderate agreement. However, they did not agree for other parameters such as TCO2, BE ecf, BE B, Hb, Hct, sO2, Na+, and pO2, therefore, reference values for each parameter were set for GEM and EDAN.